Termite Drill-and-Treat Calculator

Two separate calculations, kept distinct because the label treats them separately.

Slab / footing drill-and-treat

hole count     = floor(run length (in) / spacing (in)) + 1
total gallons  = (rate / 10) x run length (ft) x depth (ft)
gal per hole   = total gallons / hole count

The hole count uses the fencepost formula: the first hole sits at position zero and every subsequent hole is one spacing interval farther along the run. The last gap, from the final hole to the end of the run, is always equal to or less than the spacing, so the label's "no more than 12 inches apart" constraint is satisfied. For a closed loop (the last hole meets the first), subtract one from the count.

The gallons formula uses the label's standard vertical-barrier rate. The rate field accepts the label's half-volume, double-strength substitution (2 gal / 10 ft / ft depth at 0.125% when the soil will not accept 4 gal). At the Termidor SC default of 4 gal / 10 ft / ft depth, a 100-ft run at 1 ft depth needs 40 gal spread across 101 holes, or roughly 0.40 gal per hole. Halving the depth halves the gallons; tightening the spacing increases the hole count but not the total gallons, so each hole receives less.

Hollow-block void treatment

void gallons = (void rate / 10) x block run length (ft)

The hollow-block void rate has no depth component. The Termidor SC label default is 2 gal / 10 ft of footing.

Hole count and gallons-per-hole tell you what to drill and what to inject at each hole. The termite trench gallons calculator handles the open-trench vertical barrier (same rate, no drill holes). The termiticide concentrate yield calculator converts finished gallons into bottles and concentrate, while the slab pretreatment coverage calculator covers the horizontal pre-pour barrier, which runs on a per-square-foot rate instead of this linear one.